"A number of other councils in New Zealand also operate under a name that is different to their legal name. For example, Environment Southland, whose legal name is Southland Regional Council, Environment Waikato, and Horizons, for the Manawatu/Wanganui Regional Council."
He said the requirements of the act were considered before the change.
An Internal Affairs' spokesman also confirmed the operating name change was legal.
"The council has not legally changed its name, only its brand.
"Its legal name remains that which is stated in Schedule 2 of the Local Government Act 2002: the Rotorua District Council.
"A number of councils operate on a day-to-day basis under 'brand' names, but use their legal names in all official documents," the spokesman said.